Vena cava filters are commonly used in the medical field to attempt to trap venous thrombi and to prevent them from entering and embolizing in the lungs. In an ideal situation, the vena cava filter would only be used as long as necessary, namely only as long as it would take to trap the one or more thrombi of particular and potential concern.
In view of the foregoing, it would be advantageous to have a mechanism to noninvasively detect a thrombus, or other blood particulate matter of a sufficient size, within a vena cava filter so to potentially minimize the implantation period.